As methods for producing crystalline polyoxyalkylene polyols with a high isotacticity via ring-opening polymerization of alkylene oxides, various methods using catalysts have been known.
For example, a method which includes ring-opening polymerization of a chiral alkylene oxide in the presence of a catalyst commonly used to polymerize alkylene oxides (see Non-Patent Document 1), and a method which includes ring-opening polymerization of a inexpensive racemic alkylene oxide in the presence of a complex catalyst which has a particular bulky chemical structure, have been known in the art.
As the method involving particular catalysts, some methods are known, which includes use of a catalyst prepared by contacting a lanthanoid complex with an organic aluminum (see, for example, Patent Document 1), and which includes reacting, in advance, a hydroxy compound with a bimetallic μ-oxoalkoxide (see, for example, Patent Document 2).
Also known is a method for producing a polyoxyalkylene polyol with a very high isotacticity, which includes use of a salen complex as a catalyst (See, for example, Non-Patent Document 2).
However, methods, for example, including ring-opening polymerization of a chiral alkylene oxide are disadvantageous in cost because the method requires industrially-expensive chiral alkylene oxide.
The method using a racemic alkylene oxide and a particular catalyst is also disadvantageous in cost. The method requires a large amount of the complex catalyst which is unrecoverable in an active state, although the complex catalyst used in the method is expensive. Thus, the method is disadvantageous in cost. In addition, a crystalline polyoxyalkylene polyol produced by this method is insufficient in isotacticity.
The above method using a salen complex as a catalyst provides polyoxyalkylene polyols having an ester moiety at one end, and having a molecular weight of 52,000 or larger. Thus, the product polyoxyalkylene polyols are inconvenient to use as a raw material of a diol component for producing polyurethane resins, polyester resins, and the like, in view of poor reactivity.    Patent Document 1: JP-A 11-12353    Patent Document 2: JP-T 2001-521957    Non-Patent Document 1: Journal of the American Chemical Society, 1956, Vol. 78, No. 18, p. 4787-4792    Non-Patent Document 2: Journal of the American Chemical Society, 2005, Vol. 127, No. 33, p. 11566-11567